Endothermic processes

Key Questions

• Why does an endothermic reaction occur?

  Answer:

  Because the driving force of chemical change is NOT enthalpy but ENTROPY....

  Explanation:

  I can quote TWO examples of spontaneous endothermic change, and the first has a highly practical application. Have you ever seen those cold packs used in sports-medicine? These consist of a pack of SOLID ammonium nitrate, and there is a little blister of water. To apply, the blister is broken, AND ALL the ammonium nitrate goes up into solution...and this is occasioned with SUBSTANTIAL HEAT LOSS FROM the surroundings...i.e. #"spontaneous endothermic change"#. This is topically applied to the sprain, wound, swelling of an injured athlete..

  #NH_4Cl(s) +Deltastackrel(H_2O(l))rarrNH_4^+ +Cl^-#

  And a reaction that may be demonstrated in a first year lab is the reaction between barium hydroxide hydrate and ammonium thiocyanate…

  #Ba(OH)_2*8H_2O+2NH_4(SCN)_2(s) +Deltararr Ba(SCN)_2(aq) + 2NH_3(g)uarr+10H_2O(l)#

  And here the release of ammonia gas provides an entropic driving force to the reaction...

  For both reactions, a lot of heat is taken in from the surroundings, and you may see the sides of the flask become frosty as water condenses on the surface....

  How does entropy increase in the given examples...?

  anor277 · 2 · Jun 21 2018

• How do endothermic processes affect melting ice cubes?
• Why is melting ice an endothermic reaction?
• Why is an endothermic reaction cold?
• How do endothermic processes affect forming a cation from an atom in the gas phase?
• How do endothermic processes affect cooking an egg?
• Why are endothermic reactions useful?
• Why is mixing water with potassium chloride an endothermic process?
• How is an endothermic reaction identified in an equation?
• How does an endothermic reaction change the entropy of the surroundings?
• Why is the reaction of barium hydroxide octahydrate crystals with dry ammonium chloride an endothermic reaction?
• How can I explain exothermic reactions in terms of bond breaking?
• How can I explain an exothermic reaction graphically?
• What is an example of an endothermic process practice problem?
• What are some examples of endothermic processes?
• Question #07b6f
• Question #d46e8
• In which type of chemical reaction is heat absorbed from the surroundings?
• Where does the energy come from which is needed for an endothermic reaction?
• What is the #"Ostwald process"#?
• If the heat of reaction is written on the reactant side of a chemical equation, what does that indicate about the reaction?
• How do you determine a reaction that is endothermic?
• What is the effect of increasing the temperature of an endothermic reaction mixture at equilibrium? Of decreasing the temperature?
• What type of chemical reaction will absorb more energy than it releases?
• Why is the dissolution of potassium nitrate ENDOTHERMIC?
• How can dissolution of a solute in a solvent occur, even if the dissolution is ENDOTHERMIC?
• The reaction between sodium chloride and water is slightly endothermic. Why does the reaction occur?
• In an endothermic reaction at equilibrium, what is the effect of raising the temperature?
• Is rust formation an endothermic reaction because it absorbs energy?
• A chunk of ice at room temperature melts, even at though the process is endothermic. Why?
• How do you tell the difference between an endothermic reaction and an exothermic reaction?
• What are the characteristics of an endothermic reaction?
• What is an endothermic reaction?
• During an endothermic phase change, what happens to the potential energy and the kinetic energy?
• What is endothermic vs exothermic reactions?